The present invention relates to a rubber composition or, more particularly, to an acrylic rubber composition capable of giving a vulcanized rubber article having excellent heat resistance, weatherability, oil resistance and surface lubricity and a foamable acrylic rubber composition which gives a cellular spongy rubber article having excellent properties.
It is known that, among various types of acrylic rubber compositions, those having vinyl group-containing organosilicon groups in the molecule are widely used as a material of automobile parts and general-purpose industrial articles shaped by the method of compression molding, injection molding and extrusion molding by virtue of their excellent characteristics that the vulcanizates thereof have excellent heat resistance and very low permanent compression set in addition to the advantageous vulcanizability behavior that vulcanization of the composition compounded with an organic peroxide as a vulcanizing agent can proceed rapidly after a short induction period to be completed within a short time so that fully vulcanized rubber articles can be obtained in a simple vulcanization process under normal pressure without necessitating troublesome treatments such as post-vulcanization.
The acrylic rubber composition of this type, however, has a defect in respect of the poor surface lubricity and hence poor moldability as well as low slipperiness of the surface of vulcanized articles to have less usefulness. Therefore, it is eagerly desired to solve this problem for the acrylic rubber compositions of both of the unfoamable and foamable types.